When you’ve been keeping reef tanks for a decade or more than are a number of good practices that become so ingrained and second nature that we naturally take them for granted. Sometimes we don’t even realize we’re doing something out of the ordinary until someone else points it out.
One of these common habits is the practice of rinsing frozen foods, especially Piscine Energetics frozen mysis shrimp. Also known as PE Mysis, this food is one of the unrivaled ‘superfoods’ for saltwater aquariums but that high density nutrition does come with a caveat.
The high latitude lake where PE Mysis come from stimulates these crustaceans to produce a lot of lipids, fats & oils, and these are packaged right along with the shrimp. If you’ve got a huge reef tank with low nutrients, tons of fish and lots of corals then by all means go ahead and throw cubes in to thaw in the tank. But if you’ve got an average normal size reef tank you really should be rinsing PE Mysis before feeding it.
I generally do this in two cycles, using a tall jar with an inner lip to catch shrimp while skimming off the thawed water. In the first thaw you can easily see both how cloudy the water is, and how much fatty oil builds up at the surface. Doing just one rinse should remove about 75% of the loose oils but I like to do a second rinse just to make sure most of the free fats will be removed.
These are gentle rinses that don’t affect the nutritional quality of the shrimp themselves, but significantly reduce how much raw oil goes into the tank and aquarium water. Without rinsing a feeding of PE Mysis shrimp you might collapse your protein skimmer foam for several hours, but with a rinse, you can shorten this period to 30 minutes or less.
If you’ve got a lot of fish and are heavy handed with the frozen foods, your reef tank will thank you for getting the loose oils out before feeding PE Mysis to your reef. So many aquarists just skip this step and cause all kinds of nutrient, cloudiness and algae problems in their reef tank. PE Mysis is unrivaled in its nutrition for marine fish but don’t go adding unnecessary nutrients to your reef water just because you don’t take a couple minutes to rinse this frozen treat.